1. Field of the Invention
The invention relates to tire pressure measurement apparatuses and more particularly to an apparatus having a structure for fastening in an automobile tire in a universal joint type fashion and for wirelessly sending pressure of the tire to a driver.
2. Description of Related Art
Pressure of a tire of a car is critical to car safety. It is understood that insufficient pressure of tire increase fuel consumption and excessive pressure of tire may explode when driving. Thus, there is a trend of installing a tire pressure measurement apparatus for wirelessly sending tire pressure to a driver.
A conventional tire pressure measurement apparatus 900 having means for wirelessly sending tire pressure to a driver is shown in FIG. 7. The apparatus 900 includes a housing 920 having a central channel 924 with a dome-shaped opening at one end, a threaded valve 940 having a dome-shaped head 942 rotatably mounted in the opening of the channel 924, and a threaded fastener (e.g., screw) 960 driven through the channel 924 into the head 942 to assemble the housing 920 and the valve 940. The housing 920 is adapted to pivot about the head 942 to adjust its position relative to the surface of a wheel rim.
However, the conventional tire pressure measurement apparatus 900 of FIG. 7 has the following disadvantage: the housing 920 may vibrate laterally about the valve 940 due to centrifugal force when driving. As such, the screw 960 may loosen and malfunction.
For eliminating the above disadvantage, another conventional tire pressure measurement apparatus 900 having means for wirelessly sending tire pressure to a driver is shown in FIG. 8. The apparatus 900 includes a housing 920 having a central channel 924 with a rectangular mouth at one end, a threaded valve 940 having a projecting head 944 with four flat surfaces perpendicular to each other rotatably mounted in the mouth of the channel 924, and a threaded fastener (e.g., screw) 960 driven through the channel 924 into the head 944 to assemble the housing 920 and the valve 940.
However, the conventional tire pressure measurement apparatus 900 of FIG. 8 has the following disadvantages: Its installation is somewhat difficult this is because the valve 940 is mounted on the wheel rim using a nut (not shown). It is time consuming to correctly mount the apparatus 900 on the wheel rim due to complimentary engagement of the head 944 with the mouth of the channel 924. An incorrect assembly of the head 944 in the mouth of the channel 924 can loosen of the housing 920.
Thus, the need for improvement still exists.